The most common type of cancer in the United States is prostate cancer. The United States National Cancer Institute estimates that more than 238,000 new cases will occur in the United States in 2013. Although the incidence is high, so is the survival rate. Treatment options for localized prostate cancer include radiation therapy, radical prostatectomy, hormone therapy, and combinations thereof. External beam radiation is one of the more commonly used treatment options. One of the adverse side effects of radiation treatment for prostate cancer is erectile dysfunction, resulting from radiative collateral damage to the penis and penile bulb. The resultant erectile dysfunction may and often does have a significant impact on a patient's quality of life. Accordingly, a substantial need exists for a treatment regimen capable of reducing the severity and/or incidence of erectile dysfunction following radiation therapy for prostate cancer.
One study, self-acknowledged as suffering from a number of weaknesses that limit the value of the resultant data, including an insufficient number of subjects, an insufficient number of adverse events, an insufficient percentage of participants completing the program, and reliance upon participant self-evaluation and self-reporting, found that administration of 200 mg/day of soy isoflavone, containing a ratio of 1.1:1:0.2 genistein:daidzein:glycitein, during and after radiation therapy for prostate cancer, had the potential to ameliorate radiation toxicity, including the adverse side effect of erectile dysfunction. Ahmad, I., Forman, J., Sarkar, F., Hillman, G., Heath, E., Vaishampayan, U., Cher, M., Andic, F., Rossi, P., and Kucuk, O., (2010) Soy Isoflavones in Conjunction With Radiation Therapy in Patients With Prostate Cancer Nutrition and Cancer, 62(7), 996-1000. Other clinical trials found no beneficial effects of genistein or soy isoflavones.
The treatment regimen disclosed in the Ahmad et al. article inadequately mitigates the adverse side effect of erectile dysfunction following radiation therapy for prostate cancer.
Hence, a substantial need continues to exist for a method of mitigating the sexual adverse effect of erectile dysfunction associated with radiation therapy for prostate cancer.